Rain and storm for Cpt

Segg

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Yep, ours too. A 100m^2 roof with 25mm of rain equals 2500 liters!



Gotta watch those interconnection and overflow pipes, particularly when there is heavy rainfall. Running water can undermine the tanks, and do quite a lot of damage...

I find it ironic that all the tanks are now full, just when our garden doesn't need any watering...
How long will those tanks last you? In Joburg my gardener will empty my 2kl in 45 minutes with the pump running....
 

Gordon_R

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How long will those tanks last you? In Joburg my gardener will empty my 2kl in 45 minutes with the pump running....
My point was that we have just had 40mm of rain, and the garden will not need watering during winter. That water would be more useful later in the year, but most setups don't have nearly enough tanks to store more than a month's rainfall, which is useless in Cape Town with its 6 month long hot, dry and windy summer season.

Unless you have a very deep underground reservoir, the area of the tank will be larger than the area that it can irrigate. In addition on most properties the roof is smaller than the garden, so the collection ratio is less than 1:1. Sad to say, but rainwater tanks are mostly an expensive feel-good virtue-signalling trend, triggered by the recent drought.
 

biometrics

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My point was that we have just had 40mm of rain, and the garden will not need watering during winter. That water would be more useful later in the year, but most setups don't have nearly enough tanks to store more than a month's rainfall, which is useless in Cape Town with its 6 month long hot, dry and windy summer season.

Unless you have a very deep underground reservoir, the area of the tank will be larger than the area that it can irrigate. In addition on most properties the roof is smaller than the garden, so the collection ratio is less than 1:1. Sad to say, but rainwater tanks are mostly an expensive feel-good virtue-signalling trend, triggered by the recent drought.
Interesting...

Basically good to flush poop during day zero.
 
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Geoff.D

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But the tanks are useful when a regulated irrigation system is used ( drip irrigation) and to help top up pools. Just like with standby power, one has to mostly NOT undertake such things purely on financial grounds.
Our monthly water usage during no restrictions is about 8 kl per month. I would need to erect 4 2.5 Kl tanks to make up for one month's total water usage.
 
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Gordon_R

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Most of the flooded roads were due to blocked drains, which is a common problem with autumn leaves at the start of the rainy season: https://www.news24.com/SouthAfrica/News/flooding-hit-parts-of-cape-town-as-winters-first-heavy-downpour-wreaks-havoc-20190604
Emergency personnel assisted to clear part of the N2 outgoing under the railway bridge before Liesbeek Parkway. The freeway was down to a single lane which has caused a major tailback along the hospital bend and Nelson Mandela Boulevard, stretching into the city.

He said central mobile emergency units managed to clear a blocked drain on the N2 outbound before Liesbeeck Parkway.
Same story a few years ago. A single blocked drain reduced the busy N2 down to one lane in the middle of rush hour!?
 

Azg

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Gordon_R

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The SAWS reports a few impressive rainfall totals (mostly near the mountains) during the 24 hours to 8am on Wed 5th: http://www.weathersa.co.za/images/data/climate/nr_daily_rai.pdf

Highest include Ceres 73mm, Kirstenbosch 59mm, Molteno Reservoir (CBD) 40mm, Paarl 35mm, etc. Most other places in the SW-Cape received 10-20mm.

Edit: Some rain is possible later this afternoon (Wed 5th), with snow possible over the highest mountain peaks of the SW-Cape. The next major cold-front is only likely around Wed 12th.
 
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Agent_Smith

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Wow, it is coming down! I have my headphones in watching cricket and I can't hear the commentary. Traffic is going to be a doozy today :rolleyes:
 

Chuckmyster

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starting to come down nicely in Paarden Eiland now
Looking forward to the Jetski ride home to Somerset West at 5pm :)
 

Gordon_R

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Are you guys getting rain ^ This thread seems way to dead
It has been extremely dry for most of this month, and the situation is somewhat concerning. A few cold-fronts have brought some rain over the mountains, with a little inflow into the dams, but not much elsewhere.

Rain and very cold conditions are predicted for Fri 21st, but still well below the seasonal average.
 

Geoff.D

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The AAO index turned positive on the 3rd June 2019. The index is currently at +2. The current 7-day forecast shows no signs that the index will move towards 0 where it should be or even negative until after the 22nd June.
Hence the cold fronts are passing South of the country, bringing very little rain to our shores. The outcome is minimal rain for the whole of June can be expected.
Certainly, the dams are holding their own at the moment, but general winter rainfalls are just not where they should be .
 

MirageF1

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And sitting here outside in Constantia my skin is burning as the sun beats down with the ferocity of a summers day! Forecast was 22, I reckon it's close to 25C and nigh on mid winter!

Guess at least ones laundry dries better on the line than in the UK winter:)
 

Segg

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It has been extremely dry for most of this month, and the situation is somewhat concerning. A few cold-fronts have brought some rain over the mountains, with a little inflow into the dams, but not much elsewhere.

Rain and very cold conditions are predicted for Fri 21st, but still well below the seasonal average.
Hows the rest of the season looking so far?
 

Gordon_R

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Hows the rest of the season looking so far?
I don’t do long-range forecasts. 7-10 days is the limit of meaningful predictions.

After Fri 21st looks like a few more dry days, but rain could arrive anytime in mid-winter.
 

Geoff.D

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Very poor outlook for the rest of the month. Even the blip on 21-22 is going to generate very little rain and run off.
 

Gordon_R

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There is plenty of rain south (and east) of us, but not much is reaching land. Chart for the 7 days from Tues 18th to Mon 24th.

totp_week1_s[20190618-25].gif
 
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